Loss of susceptibility as a novel breeding strategy for durable and broad-spectrum resistance

Recent studies on plant immunity have suggested that a pathogen should suppress induced plant defense in order to infect a plant species, which otherwise would have been a nonhost to the pathogen. For this purpose, pathogens exploit effector molecules to interfere with different layers of plant defense responses. In this review, we summarize the latest findings on plant factors that are activated by pathogen effectors to suppress plant immunity. By looking from a different point of view into host and nonhost resistance, we propose a novel breeding strategy: disabling plant disease susceptibility genes (S-genes) to achieve durable and broad-spectrum resistance

Kinetic analysis of forced aeration composting - II. Application of multilayer analysis for the prediction of biological degradation

Extensive pilot-scale composting tests for organic solid waste were conducted under different modes of aeration, to investigate vertical temperature distributions and their effect on biological degradation at different heights of the composting mass. The modes of aeration applied were upflow, downflow, alternate upflow/downflow, and internal air recirculation. Temperatures at different heights of the composting mass were continuously monitored. Results show that (i) significant variation in temperature and biodegradable volatile solids (BVS) degradation occur in the composting mass along the vertical direction when unidirectional aeration is applied; (ii) application of alternate upflow/downflow aeration or periodic mixing greatly reduces vertical gradients in temperature and biodegradable volatile solids (BVS) degradation; and (iii) the rate and extent of degradation in different layers of the composting mass can be quantitatively predicted by applying a combination of multilayer analysis and a previously established temperature-dependent first-order reaction model. | Extensive pilot-scale composting tests for organic solid waste were conducted under different modes of aeration, to investigate vertical temperature distributions and their effect on biological degradation at different heights of the composting mass. The modes of aeration applied were upflow, downflow, alternate upflow/downflow, and internal air recirculation. Temperatures at different heights of the composting mass were continuously monitored. Results show that (i) significant variation in temperature and biodegradable volatile solids (BVS) degradation occur in the composting mass along the vertical direction when unidirectional aeration is applied; (ii) application of alternate upflow/downflow aeration or periodic mixing greatly reduces vertical gradients in temperature and biodegradable volatile solids (BVS) degradation; and (iii) the rate and extent of degradation in different layers of the composting mass can be quantitatively predicted by applying a combination of multilayer analysis and a previously established temperature-dependent first-order reaction model.link_to_subscribed_fulltex

Vane shear strength in dewatered sludge from Hong Kong

The vane shear strength and total solids content of dewatered sludge from Hong Kong were determined in order to evaluate their geotechnical suitability for disposal in landfills. The results obtained indicate that (i) the total solids and vane shear strength of dewatered sludge from different treatment plants varied considerably depending on the type of sludge and dewatering method; and, (ii) percent total solids alone is not sufficient to guarantee geotechnical stability in terms of vane shear strength. The critical state model for soils provided a good fit for the characteristics relationship between vane shear strength and total solids, which can be used to estimate vane shear strength from total solids only. No relationship between volatile solids and vane shear strength was found. The results of the laboratory vane shear test correlated well with those obtained by a pocket shearmeter indicating the usefulness of this method for rapid determination of vane shear strength on site. Some factors that influence vane shear strength were briefly evaluated. Implications of the results for sludge management with special emphasis on dewatering and landfilling were discussed.link_to_subscribed_fulltex

Vane shear strength of Hong Kong dewatered sludge and its implication for landfilling

Congress Theme: Operation and Management, Landfill and Sludge Managemen

Effect of air recirculation on single-reactor and two- reactor composting system

A modified accelerated forced aeration composting process was investigated to improve the rate and extent of organic wastes degradation. Composting tests were performed in two stages of 20 to 30 days duration each, using either a single reactor or a two-reactor system. Temperature at different depths of the composting mass, air velocity and pressure were continuously monitored by the datalogger. Air flow was continuous or intermittent depending on temperature. Oxygen content in the spent air was regularly measured. The product stability was determined by the self-heating test.link_to_subscribed_fulltex